Lead-in wire contacting apparatus



Nov. 12, 1957 1... w. KIMBALL EIAL LEAD-IN WIRE CONTACTING APPARATUS Filed Nov. 14, 1955 INVENTORS: LlW/Ff/Vf W ff/MML Unite States Patent 2,812,994 LEAD-IN WIRE CONTACTING APPARATUS Lawrence W. Kimball, Bedford, and Stanley C. Shappell, West Boxford, Mass., assignors to Sylvania Electric Products Inc, Salem, Mass., a corporation of Massachusetts Application November 14, 1955, Serial No. 546,336 7 Claims. (Cl. 316-32) This invention relates generally to electrical contact apparatus and more particularly to apparatus for making temporary electrical connections to the lead-in wires of electric lamps and the like during the manufacture thereof.

Apparatus according to our invention is especially useful for providing current to lead-in Wires of electric discharge lamps, such as fluorescent lamps, during manufacture. The device is particularly useful for providing current to filamentary electrodes through a pair of leadin wires at one end of a lamp.

The electrodes must generally be electrically energized during certain stages of an exhaust process through which the lamp is carried on an exhaust machine. Moreover, since contact bases are not applied to the lamp until after the exhaust process, the voltage for energizing the filamentary electrodes must be applied directly to the lead-in wires, which are easily deformed and difiicult to orient.

One means for applying the proper voltage is to provide two parallel, stationary metal tracks, each being in position to be contacted by a lead-in wire as the lamp is carried over a predetermined path by a head or heads on the exhaust machine. Proper contact in such apparatus depends upon the resilience of the lead-in wires, and requires their precise orientation.

Another means of contacting the lead-in wires is to provide two semi-circular contacts, spaced apart circumferentially by an insulating air gap to form a split ring, with one side of a single-phase electrical line connected to each contact. The ring is placed around an exhaust head on an exhaust machine, and moves with the lamp carried by said head, the lead-in wires being placed in contact with the split ring. However, the electrode will not be energized if both lead-in wires fall on a single contact, or if a lead-in wire drops through the gap between the contacts, so again precise orientation of the lead-in wires is required.

Accordingly, an object of the present invention is to make such precise orientation unnecessary, that is, to insure that energization of the electrode will be substantially independent of the axial orientation of the lead-in wires.

In one embodiment of our invention, such independence is achieved by the use of three circular contact segments, joined to form a ring with the segments insulated from each other. The insulation is provided by leaving small circumferential gaps between the segments. Each segment is connected to one wire of a three wire, threephase line. Each such segment will then extend over an angle small enough to reduce the probability of both lead-in wires contacting a single segment. Were only two segments used, a small deviation in alignment of the wires would allow two wires to fall on a single segment; with three segments, the alignment would have to be 60 off for that to happen.

As long as each lead-in wire contacts a different seg- 2 ment, the proper voltage will be applied to the lead-in wires, because the magnitude of the voltages between any two of the diflferent segments will be the same with three-phase supply.

Moreover, the gaps between segments are made small and are offset at an angle from the radius of the ring, so that the probability of a lead-in wires falling in the gap between segments is vanishingly small.

With such a construction, a lead-in wire, instead of falling in a gap and failing to make any contact at all, will be more likely to fall across a gap and contact two adjacent segments.

As long as only one lead-in wire contacts two segments, the current through the lamp will still have the proper value for energization, provided that currentlimiting resistors are used in series between each segment and the line, and that these resistors not only have the proper value to allow the desired current through the electrode, but also have a resistance high compared to that of the electrode to be energized. The latter can be achieved by having the voltage of the three-phase source considerably greater than that required to pass the proper energizing current through the lamp, so that a sutficiently high series resistance can be used. The use of sufficient series reistance keeps the three-phase line balanced even when two segments are connected together.

The reason for the proper current flow even when two segments are shorted is not readily apparent but can be summarized as follows: One pair of the contacts will be short-circuited by the lead-in wire which bridges them. Accordingly, no current from that phase will pass through the electrode. However, current from each of the other phases will pass through the lamp; that is, current will pass to the third segment from each of the other phases. Since the currents from each of these two phases will be established by equal voltages differing in phase by and limited by substantially equal resistances, they will be substantially equal currents differing in phase by 120". The net current through the electrode will be the vector sum of those two currents, which will have the same magnitude as either of the two component currents, and be midway between the two in phase.

Therefore even if a lead-in wire shorts two of the segments, the proper energizing current will flow through the lamp.

Of course, if each of the lead-in wires fall across a gap, then the electrode itself will be short-circuited and the current through it will be insufficient for proper energization. But the probability of such short-circuit of two different gaps is extremely small, especially if the lead-in wires are bent to extend in roughly opposite directions, that is about apart, because under such circumstances if one wire falls across a gap, the other will fall directly on a segment. For both wires to fall across gaps, one wire would have to be 60 out of line.

Accordingly, if the wires are roughly aligned in opposite directions, the filament will be properly energized, no matter how the general direction of the wires is oriented with respect to the segments.

The manufacture of lamps is thereby greatly facilitated, because elaborate apparatus to orient the lamp in the exhaust machine is unnecessary. When, for example, apparatus like that of copending application, Serial No. 343,842, filed by Dodge and Kimball, March 23, 1953, now U. S. Patent 2,726,799, is used, the lamps can be allowed to roll onto the exhaust machine in any orientation they may assume.

Further objects, advantages and features of our invention will be clarified from the following detail de- 3 scription of an illustrative embodiment thereof, taken in connection with the accompanying drawings in which: Figure 1 is a view in front elevation of a portion of an exhaust head including lead-in wire contacting apparatus according to our invention.

Figure 2 is a view in end elevation taken iron the line 22 of Figure 1;

Figure 3 is a circuit diagram showing electrical components associated with the contacting apparatus.

Our apparatus will now be described in detail with initial reference to Figure 1 in which is shown a movable assembly, associated with one end of a fluorescent lamp during its manufacture, in a machine such as that disclosed in copcnding U. S. patent application, Serial No. 343,842, filed by Dodge and Kimball March 23, 1953, now U. S. Patent 2,726,799. In such machines, lamps are carried through a fixed path by a pair of exhaust heads, each of the latter being in communication with the interior of the lamp through an exhaust tube. Burner plate 20 is movable axially with respect to a lamp indicated fragmentarily at 22. The rod 24 supports the plate 22 at one end and at the other engages suitable cam means for providing axial motion as the head moves over its fixed path. It will be understood at the outset that the apparatus shown in Fig. 1 is provided at each end of the machine.

The lamp 22 comprises a glass envelope 26, a cathode 28 enclosed therein, a pair of lead-in wires 30, each in electrical communication through the envelope '26 with a different end of the cathode 2S, and an exhaust tube 32 in communication with the interior of the lamp 22. Shown in Figure 1, in addition to parts specifically concerned with our invention, is a cradle 34- mounted on a post 36, for supporting the lamp 22 when it is first introduced into the exhaust machine. The post 36 is in turn supported on the burner plate 20 which is attached to rod 24 by a latch 38 and a nut 40.

Ring 42 of suitable heat resistant and electrical insulating material, such as an asbestos composition known as Transite, is fixedly mounted on the plate 20 by means of brackets 4-4. The ring 42 encompasses a set of three similar arcuate electrodes 46, 48 and 50, best seen in Figure 2. Each electrode is in communication with an appropriate point of a three-phase power source through a wire 51 extending between a terminal stud 52 and an insulator block 54. Each wire St is connected at the block 5 to a flexible finger 56 which contacts a commutator track 58 during an appropriate portion of the ex hausting cycle. The three tracks 58 are co-extensive on the machine and each is insulatedly supported on a suitable stationary frame element adjacent the path of the lamp. Each of the tracks 58 is connected to the power source by a conductor 60. 7

Referring now to Figure 3, a source of three phase power is here illustrated schematically. It comprises a transformer indicated at 62, which may be employed in combination with the electrodes 46, 48, St), for energizing cathodes of fluorescent lamps. The transformer 62 includes secondary windings 64, 66 and 63 arranged in a delta circuit, the junction between windings 63 and 6 1 6d and 66, and 66 and es being more particularly identitied for clarity by the letters A, B and C respectively. The electrode 46 is connected to junction B through a variable resistor '79 and the electrodes 48 and 5t are similarly connected to junctions C and A through adjustable resistors ?2 and 74, respectively. Equal voltages of between 25 and 130 volts and 120 out of phase with one another are produced across each of the windings 64}, 66 and 65, and resistors 7t), 72 and 74 are adjusted'to be as nearly equal as possible.

Thus whether the cathode 28 having lead-in wires 3%) is connected between electrodes 48 and 50, as illustrated in Figure 3, or between electrodes 48 and46, or between electrodes id-and-Stl, the power dissipation in the cathode 28 is the same. It is also to be appreciated that if one of the lead-in wires contacts two electrodes such as 46 and 48 while the other contacts the third electrode Stl, the power dissipation within the cathode 23 will also be substantially the same. Under these circumstances a current flow through a portion of the lead-in wire shorted between the electrodes 46 and 48 will be provided by the winding 66 and limited by the resistors 70 and 72 which current flow will have no effect on power dissipation within the cathode 28. Flowing through the cathode 28 will be current caused by voltages across windings 64 and 63, which voltages are 120 electrical degrees apart. The eifective current flow produced by the windings 64 and 68 is the vector sum of the currents from the two windings, said sum being equal to and differing in phase by 6() electrical degrees from each of the individual circtuts.

When received by the exhaust machine, the lamp 22, which has its lead-in wires 30 disposed radially relative to the axis of the lamp 22 and more than 126 apart, is supported by a cradle 34 near each end. As the lamp 22 is received the plates at both ends are retracted outwardly to permit insertion, between the rings 42, of exhaust tubes 32 extending from each end of the lamp 22. As the plates 2% proceed along the path on the exhaust machine, they are moved closer together, each efiaust tube 32 then passing through an opening 76 in the plate 20 into an exhaust head, not shown. The ring 42, in moving inwardly, brings the inner face of the electrodes into engagement with the lead-in wires 30, thus establishing electrical communication as already described. It is to be additionally noted that the ends of the electrodes 46, 48, 5t are angularly disposed relative to a radial line of the ring 42 to prevent passage of a lead-in wire 3% between two electrodes without contacting either.

In a typical example of apparatus according to the invention, a line voltage of 96 voltswas used, with resistors 70, 72, 74, of about 50 ohms each in series to drop the voltage across the filamentary electrodes or cathodes to between 10 to 25 volts.

While we have described a particular embodiment of the invention, various modifications can be made without departing from the spirit of the invention. For example, the metal contact segments can be made of other than arcuate shapes, as long as they can be placed together to form a figure closed except for the insulating gaps therebetween.

What we claim is:

1. In a machine formanufacturing an electrical device having a pair of lead-in wires extending in spaced-apart relationship from said device, electrical contacting apparatus comprising: a base of electrical insulating material; three contacts mounted on said base and electrically insulated from one another; connections from said electrodes to a source of three-phase power, with one phase of said source connected between each pair of said contacts; and means for holding said electrical device with each of said lead-in wires in engagement with one of said contacts.

2. In a machine for manufacturing an electrical device having a pair of oppositely arranged lead-in wires, electrical contacting apparatus comprising: a base member of electrical insulating material; three arcuate contacts, electrically insulated from one another, mounted on said member and defining a ring; connections from said contacts to a source of three-phase power, with one phase of said source connected between each pair ofsaid contacts; and means for holding said electrical device with each of said lead-in wires in engagement with one of said contact pieces. 7 3. a machine for manufacturing an electrical device having a pair ot oppositely arranged lead-in wires, electrical contac ing apparatus comprising: a base member iwulating material; three arcuate contacts,

ed from one another, mounted Mining a ring, adjacent ends of said conon said 7 tacts forming, between them, a gap which is angularly oriented relative to a radial line in a transverse plane of said ring; connections from said contacts to a source of three-phase power, with one phase of said source connected between each pair of said contacts; and means holding said electrical device with each of said lead-in wires in engagement with one of said contact pieces.

4. In a machine for manufacturing an electrical device having a pair of lead-in wires extending in spaced-apart relationship from said device, electrical energizing apparatus comprising: a base of electrical insulating material; three contacts mounted on said base and electrically insulated from one another; a three-line source of threephase electrical power, each line connected to one of said contacts; and means for bringing each of said lead-in wires into engagement with at least one of said contacts.

5, In a machine for manufacturing an electrical device having a pair of oppositely arranged lead-in wires, electrical energizing apparatus comprising: a base member of electrical insulating material; three similar arcuate contacts electrically insulated from one another, mounted on said member and defining a ring; a three-line source of three-phase electrical power, each line connected to one of said contacts; and means for bringing each of said lead-in wires into engagement with at least one of said contacts.

6. In a machine for manufacturing an electrical device having a pair of oppositely arranged lead-in wires, electrical energizing apparatus comprising: a base member of electrical insulating material; three similar arcuate contacts, electrically insulated from one another, mounted on said member and defining a ring, adjacent ends of said contacts forming, between them, a gap which is angularly oriented relative to radial line in a transverse plane of said ring; a three-line source of three-phase electrical power, each line connected to one of said contacts; and means for bringing each of said lead-in wires into engagement with at least one of said contacts.

7. In a machine for manufacturing a tubular electric lamp having a two-ended internal element and a pair of lead-in wires, oppositely arranged at one end of said lamp and each in electrical communication with one end of said element, apparatus for energizing said element through said wires, said apparatus comprising: three generally arcuate contacts arranged to form a ring having insulating gaps between the ends of adjacent contacts, each contact being electrically connected to a line of a three-phase, three-line power source; and means for bringing each of said lead-in wires into engagement with at least one of said contacts.

References Cited in the file of this patent UNITED STATES PATENTS 1,394,515 Buck Oct. 18, 1921 1,853,734 Lang Apr. 12, 1932 2,426,246 Skinker Aug. 26, 1947 2,573,416 Eddy Oct. 30, 1951 

